package PTA.Pta_ch02;
import java.util.Scanner;
public class ex22 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        int c=sc.nextInt();
        double d;
        d=(a+b+c)*1.0/3;
        System.out.printf("aver="+"%.6f",+d);
    }
}
